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State PCS PYQPrelims 2023

BPSC – Combined Competitive Examination · Question 18

How do COVID vaccines stimulate an immune response?

  1. By introducing live attenuated SARS-CoV-2 virus
  2. By introducing real SARS-CoV-2 virus
  3. By introducing a harmless piece of SARS-CoV-2 virus
  4. By introducing antibodies against SARS-CoV-2 virus
Show answer & explanation

Answer: (C) By introducing a harmless piece of SARS-CoV-2 virus

Explanation

Vaccines (mRNA, vector, protein, inactivated) expose the body to harmless viral parts so it makes its own antibodies.

  • (A) Incorrect

    Wrong: most approved COVID vaccines are not live-attenuated.

  • (B) Incorrect

    Wrong: unsafe; not how vaccines work.

  • (C) Correct

    Correct: they present a harmless antigen (e.g. spike protein or its code) to train immunity.

  • (D) Incorrect

    Wrong: that is passive immunisation, not vaccination.